This invention relates to a valve apparatus for the disposable circuit of a mechanical ventilator.
Patients who have respiratory problems often require a mechanical ventilator to aid them in breathing. These ventilators include a disposable breathing circuit to transport the air to and from the patient. Many ventilators utilize a breathing circuit with a exhalation valve in the expiratory limb of the circuit. The exhalation valve closes during the patient's inspiratory phase so that the patient's lungs inflate, and opens during the expiratory phase so that the air may exit the lungs. It is important that the valve completely close the expiratory path during inhalation and yet respond quickly to open the pathway at the appropriate time to allow exhalation.
Some earlier valves do not respond quickly and thus may not open at the appropriate time or may not provide the desired air gap. The patient's lungs must then work harder during exhalation.
Patients with damaged or collapsed lungs sometimes require a positive end expiratory pressure (PEEP), i.e. at the end of the exhalation phase a positive pressure remains in the patient's lungs. The prior valves with slow response times may have particular problems controlling PEEP.
The component of the valve that exerts the greatest control over the valve's performance is the diaphragm. The diaphragm is generally formed of a flexible material. The ease with which this diaphragm is moved into contact with or away from the valve seat governs the valve performance. Many prior valves have a diaphragm with an approximately uniform thickness throughout. These diaphragms generally have a higher resistance to movement and thus they require greater air flow to change their position from closed to open, or vice versa. Since the patient's lungs exert the force that opens the valve, the lungs are required to work harder to provide the additional force necessary to open a prior valve. This is usually undesirable since the patient will recover faster if allowed greater rest.
The present invention provides an improved valve that overcomes or substantially alleviates the problems of the prior art.